QTL analysis for sugar-regulated senescence suppports flowering-dependent and - independent senescence pathways

• The aim of this work was to determine the genetic basis of sugar-regulated
senescence and to explore the relationship with other traits, including flowering
and nitrogen-use efficiency.
• Quantitative trait loci (QTLs) for senescence were mapped in the Arabidopsis
Bay-0 · Shahdara recombinant-inbred line (RIL) population after growth on glucose-
containing medium, which accelerates senescence. The extent of wholerosette
senescence was determined by imaging the maximum quantum yield of
photosystem II (Fv ⁄ Fm).
• A major QTL on the top of chromosome 4 colocalized with FRI, a major determinant
of flowering. This QTL interacted epistatically with a QTL on chromosome
5, where the floral repressor FLC localizes. Vernalization accelerated senescence in
late-flowering lines with functional FRI and FLC alleles. Comparison with previous
results using the Bay-0 · Shahdara population showed that rapid rosette senescence
on glucose-containing medium was correlated with early flowering and high
sugar content in compost-grown plants. In addition, correlation was found
between the expression of flowering and senescence-associated genes in Arabidopsis
accessions. However, an additional QTL on chromosome 3 was not linked to
flowering, but to nitrogen-use efficiency.
• The results show that whole-rosette senescence is genetically linked to the vernalization-
dependent control of flowering, but is also controlled by flowering-independent
pathways.